Controlling pest populations is essential to human health, modern agriculture, food storage, and hygiene. There are more than ten thousand species of pests that cause losses in agriculture and the worldwide agricultural losses amount to billions of U.S. dollars each year. Accordingly, there exists a continuous need for new pesticides and for methods of producing and using such pesticides.
The Insecticide Resistance Action Committee (IRAC) has classified insecticides into categories based on the best available evidence of the mode of action of such insecticides. Insecticides in the IRAC Mode of Action Group 6 are chloride channel activators. The insecticides in this class are believed to allosterically activate glutamate-gated chloride channels (GluCls), causing paralysis of the affected insects. Glutamate has been reported an important inhibitory neurotransmitter in insects. The insecticides in this class may be avermectins-based compounds or milbemycins-based compounds. Examples of these insecticides may include abamectin, emamectin benzoate, lepimectin, or milbemectin.
Emamectin benzoate is a 4′-deoxy-4′-methyl-amino benzoate salt of avermectin B1 (abamectin). Abamectin is a mixture of avermectins containing more than 80% of avermectin B1a, which is (10E,14E,16E)-(1R,4S,5′S,6S,6′R,8R,12S,13S,20R, 21R,24S)-6′-[(S)-sec-butyl]-21,24-dihydroxy-5′,11,13,22-tetramethyl-2-oxo-(3,7,19-trioxatetracyclo[ 15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene)-6-spiro-2′-(5′,6′-dihydro-2′H-pyran)-12-yl 2,6-dideoxy-3-O-methyl-4-O-(2,4,6-trideoxy-3-O-methyl-4-methylamino-α-L-lyxo-hexapyranosyl)-α-L-arabino-hexapyranoside, and less than 20% of avermectin B1b, which is (10E,14E,16E)-(1R,4S,5′S,6S,6′R,8R,12S, 13S,20R,21R,24S)-21,24-dihydroxy-6′-isopropyl-5′,11,13,22-tetramethyl-2-oxo-(3,7,19-trioxa tetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene)-6-spiro-2′-(5′,6′-dihydro-2′H-pyran)-12-yl-2,6-dideoxy-3-O-methyl-4-O-(2,4,6-trideoxy-3-O-methyl-4-methylamino-α-L-lyxo-hexapyranosyl)-α-L-arabino-hexapyranoside.
Although the rotational application of pesticides having different modes of action may be adopted for good pest management practice, this approach does not necessarily give satisfactory insect control. Furthermore, even though combinations of pesticides have been studied, a high synergistic action has not always been found.